Bulk sodium species treatment of thin film photovoltaic cell and manufacturing method

• US 8,258,000 B2
• Filed: 08/02/2011
• Issued: 09/04/2012
• Est. Priority Date: 09/29/2008
• Status: Expired due to Fees

• Current Assignee: Stion Corporation
• Original Assignee: Stion Corporation
• Inventors: Lee, Howard W. H.
• Primary Examiner(s): Vu, David
• Assistant Examiner(s): Taylor, Earl
• Application Number:
  US13/196,825
• Publication Number:
  US 20110287574A1
• Time in Patent Office: 399 Days
• Field of Search: 438/85, 257E21466-E2147, 257/E21.483, 257/E21.485, 257/E21.497, 136/265
• US Class Current: 438/85
• CPC Class Codes: H01L 21/0237 Materials
• CPC Class Codes: H01L 21/02491 Conductive materials
• CPC Class Codes: H01L 21/02568 Chalcogenide semiconducting materials not being oxides, e.g. ternary compounds
• CPC Class Codes: H01L 21/02614 Transformation of metal, e.g. oxidation, nitridation
• CPC Class Codes: H01L 21/02631 Physical deposition at reduced pressure, e.g. MBE, sputtering, evaporation
• CPC Class Codes: H01L 31/022425 for solar cells
• CPC Class Codes: H01L 31/0322 comprising only AIBIIICVI chalcopyrite compounds, e.g. Cu In Se2, Cu Ga Se2, Cu In Ga Se2
• CPC Class Codes: H01L 31/0323 characterised by the doping material
• CPC Class Codes: H01L 31/0749 including a AIBIIICVI compound, e.g. CdS/CulnSe2 [CIS] heterojunction solar cells
• CPC Class Codes: H01L 31/186 Particular post-treatment for the devices, e.g. annealing, impurity gettering, short-circuit elimination, recrystallisation
• CPC Class Codes: Y02E 10/541 CuInSe2 material PV cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

A method for forming a thin film photovoltaic device is provided. The method includes providing a transparent substrate comprising a surface region. A first electrode layer is formed overlying the surface region. A chalcopyrite material is formed overlying the first electrode layer. In a specific embodiment, the chalcopyrite material comprises a copper poor copper indium disulfide region. The copper poor copper indium disulfide region having an atomic ratio of Cu:In of about 0.95 and less. The method includes compensating the copper poor copper indium disulfide region using a sodium species to cause the chalcopyrite material to change from an n-type characteristic to a p-type characteristic. The method includes forming a window layer overlying the chalcopyrite material and forming a second electrode layer overlying the window layer.

Claims

1. A method for forming a thin film photovoltaic device, the method comprising:

providing a transparent substrate comprising a surface region;

forming a first electrode layer overlying the surface region;

forming a copper layer overlying the first electrode layer;

forming an indium layer overlying the copper layer to form a multi-layered structure;

subjecting at least the multi-layered structure to a thermal treatment process in an environment containing a sulfur bearing species;

forming a copper indium disulfide material comprising a copper poor surface from at least the treatment process of the multi-layered structure;

subjecting at least a portion of the copper poor surface of the copper indium disulfide material to a sodium species; and

forming a window layer overlying the copper indium disulfide material.

2. The method of claim 1 wherein the subjecting of the sodium species is provided by at least one process selected from spin coating, spraying, spray pyrolysis, pyrolysis, dipping, deposition, sputtering, or electrolysis.

3. The method of claim 1 wherein the sodium species comprises sodium ions.

4. The method of claim 1 wherein the copper indium disulfide comprises a thickness of copper sulfide material, the thickness of copper sulfide material being selectively removed using a solution of potassium cyanide.

5. The method of claim 1 wherein the window layer is selected from a group consisting of a cadmium sulfide, a zinc sulfide, zinc selinium, zinc oxide, or zinc magnesium oxide.

6. The method of claim 1, wherein the subjecting to a sodium species is performed during at least a thermal treatment process characterized by a temperature ranging from about 100 Degrees Celsius to about 500 Degrees Celsius.

7. The method of claim 6 wherein the thermal treatment process is provided in an environment containing at least a sulfur bearing species comprising hydrogen sulfide in a fluid phase.

8. The method of claim 1 wherein the forming of the copper layer is provided by a sputtering process or plating process.

9. The method of claim 1 wherein the sodium species compensates for any missing copper in the copper poor surface.

10. The method of claim 1 wherein the forming of the indium layer is provided by a sputtering process.

11. The method of claim 1 wherein the forming of the indium layer is provided by a plating process.

12. The method of claim 1 wherein the copper indium disulfide material comprises a p-type semiconductor characteristic.

13. The method of claim 1 wherein the window layer comprises an n⁺-type semiconductor characteristic.

14. The method of claim 1 further comprising introducing an indium species in the window layer to cause formation of an n⁺-type semiconductor characteristic.

15. The method of claim 1 wherein the copper indium disulfide material is mixed with a copper indium aluminum disulfide or copper indium gallium disulfide.

16. A method for forming a thin film photovoltaic device, the method comprising:

providing a transparent substrate comprising a surface region;

forming a first electrode layer overlying the surface region;

forming a copper indium material by at least sputtering a target comprising an indium copper material;

subjecting the copper indium material to thermal treatment process in an environment containing a sulfur bearing species;

forming a copper poor copper indium disulfide material from at least the thermal treatment process of the copper indium material;

compensating for the lack of copper in the copper poor copper indium disulfide material using a sodium species; and

forming a window layer overlying the copper indium disulfide material.

17. The method of claim 16 the compensating is provided by at least one process selected from spin coating, spraying, spray pyrolysis, pyrolysis, dipping, deposition, sputtering, or electrolysis.

18. The method of claim 16 wherein the sodium species comprises sodium ions.

19. The method of claim 16 further comprising subjecting at least the copper poor copper indium disulfide material to a thermal treatment process characterized by a temperature from about 100 Degrees Celsius to about 500 Degrees Celsius.

20. The method of claim 19 wherein the thermal treatment process is provided in an environment containing at least a sulfur bearing species comprising hydrogen sulfide.

21. The method of claim 16 wherein the window layer is selected from a group consisting of a cadmium sulfide, a zinc sulfide, zinc selenium, zinc oxide, or zinc magnesium oxide.

22. The method of claim 16 further comprising forming a transparent conductive oxide overlying a portion of the window layer.

23. The method of claim 16 wherein the copper poor copper indium disulfide material after compensation has a p-type semiconductor characteristic.

24. The method of claim 16 wherein the window layer comprises n⁺-type semiconductor characteristic.

25. The method of claim 16 further comprising introducing an indium species in the window layer to cause formation of an n⁺-type semiconductor characteristic.

26. A method for forming a thin film photovoltaic device, the method comprising:

providing a substrate comprising a surface region;

forming a first electrode layer overlying the surface region;

forming a chalcopyrite material overlying the electrode layer, the chalcopyrite material including a copper poor copper indium disulfide region;

altering a characteristic of the copper poor copper indium disulfide region using a sodium species;

forming a window layer overlying the chalcopyrite material; and

forming a second electrode layer overlying the window layer.